The rapidly expanding Pennsylvania Railroad built viaducts in several cities to eliminate dangerous grade crossings. Wilmington's viaduct snakes for almost four miles starting northeast at Wilmington Shops (WL63), where construction began. It featured walls of building stone on concrete foundations and a fill of earth, but deep mud southwest of downtown required a switch to arch construction. Pads of concrete, eight feet deep, were poured to receive the arches, which were supposed to be stone entirely, only the supply was limited. Bricks were laid instead, in rings up to fifty-five inches deep, forming a series of arches eight feet high and forty-one feet in span. Working for the Engineering Department of the Pennsylvania Railroad, Brown promoted heavy masonry-arch construction throughout the company's works.